Visible light communication apparatus and method

ABSTRACT

Provided is a visible light communication apparatus. The visible light communication apparatus includes: a display unit that displays an image according to an image signal; a light source unit that operates as a backlight for the display unit, generates an optical signal by driving a light source based on a data signal, and outputs the generated optical signal to the display unit; a sensor unit that detects a region corresponding to a shape of a terminal which touches or approaches the display unit; and an image signal conversion unit that converts the image signal such that an image displayed in the region detected by the sensor unit is converted to a bright image having a gray level higher than a predetermined reference gray level.

This application claims priority to Korean Patent Application No.10-2010-0018528 filed on Mar. 2, 2010 in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to visible light communication.More particularly, the present invention relates to a visible lightcommunication apparatus which transmits or receives data by using thebacklight of a non self-luminous display device such as a liquid crystaldisplay (LCD).

2. Description of the Related Art

Visible light communication is communication technology that usesvisible light to transmit information. In visible light communication,data is transmitted by using visible light emitted from a light source,such as a lighting device or a backlight included a display device,where the light source transmits the data via rapid sets of pulses thatare transmitted too quickly to be seen by the naked eye.

In visible light communication, frequency allocation is unnecessary, anda large amount of data can be transmitted at high speed by thishigh-speed flickering of a light source. Due to these advantages,visible light communication is drawing attention in short-distancewireless communication, particularly in unidirectional informationprovision systems.

Attempts have been made to apply visible light communication to displaydevices such as liquid crystal displays (LCDs). However, no displaydevice employing visible light communication has been introduced yet,and virtually no research has been conducted on communication range,communication speed, communication quality, and the like.

SUMMARY OF THE INVENTION

Aspects of the present invention provide a visible light communicationapparatus and method, in which data is transmitted and received by usinga backlight of a display device as a light source for data transmission.

However, aspects of the present invention are not restricted to the onesset forth herein. The above and other aspects of the present inventionwill become more apparent to one of ordinary skill in the art to whichthe present invention pertains by referencing the detailed descriptionof the present invention given below.

According to an aspect of the present invention, there is provided avisible light communication apparatus including: a display unit thatdisplays an image according to an image signal; a light source unit thatoperates as a backlight for the display unit, generates an opticalsignal by driving a light source based on a data signal, and outputs thegenerated optical signal to the display unit; a sensor unit that detectsa region corresponding to a shape of a terminal which touches orapproaches the display unit; and an image signal conversion unit thatconverts the image signal such that an image displayed in the regiondetected by the sensor unit is converted to a bright image having a graylevel higher than a predetermined reference gray level.

According to another aspect of the present invention, there is provideda visible light communication apparatus including: a display unit havinga plurality of display blocks on which an image is to be displayed; alight source unit having a plurality of light source blocks whichcorrespond respectively to the display blocks, wherein each of the lightsource blocks is configured to output an optical signal to acorresponding one of the display blocks; and a sensor unit thatidentifies a display block corresponding to a position of a terminalwhich touches or approaches the display unit, wherein the light sourceunit is configured to generate an optical signal by driving the lightsource block corresponding to the identified display block, wherein thedriving is based on a data signal of a broadcast signal, and wherein thedriving outputs the generated optical signal to the identified displayblock.

According to another aspect of the present invention, there is provideda visible light communication method including: displaying an image on adisplay unit according to an image signal; detecting a terminal touchingor approaching the display unit; detecting a region corresponding to ashape of the terminal that touches or approaches the display unit;converting the image signal such that an image displayed in the detectedregion is converted to a bright image having a gray level higher than apredetermined reference gray level; generating an optical signal bydriving a light source based on a data signal; and outputting thegenerated optical signal to the display unit.

According to another aspect of the present invention, there is provideda visible light communication method including: displaying an image on adisplay unit according to an image signal, the display unit having aplurality of display blocks; detecting a terminal touching orapproaching any one of the display blocks; identifying a display blockcorresponding to a position of the touching or approaching terminal;generating an optical signal by driving a light source block thatcorresponds to the identified display block, wherein the driving isbased on a data signal; and outputting the generated optical signal tothe identified display block.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects and features of the present invention willbecome more apparent by describing in detail exemplary embodimentsthereof with reference to the attached drawings, in which:

FIG. 1 is a diagram illustrating the configuration of a visible lightcommunication apparatus according to an exemplary embodiment of thepresent invention;

FIG. 2 is a diagram illustrating examples of a waveform of a converteddata signal according to an exemplary embodiment of the presentinvention;

FIG. 3 is a diagram illustrating the concept of image conversionperformed by the visible light communication apparatus of FIG. 1;

FIG. 4 is a flowchart illustrating a visible light communication methodaccording to an exemplary embodiment of the present invention;

FIG. 5 is a diagram illustrating the configuration of a visible lightcommunication apparatus according to another exemplary embodiment of thepresent invention;

FIG. 6 is a diagram illustrating the concept of data transmissionperformed by the visible light communication apparatus of FIG. 5; and

FIG. 7 is a flowchart illustrating a visible light communication methodaccording to another exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Advantages and features of the present invention and methods ofaccomplishing the same may be understood more readily by reference tothe following detailed description of exemplary embodiments and theaccompanying drawings. The present invention may, however, be embodiedin many different forms and should not be construed as being limited tothe embodiments set forth herein. Rather, these embodiments are providedso that this disclosure will be thorough and complete and will fullyconvey the concept of the invention to those skilled in the art, and thepresent invention will only be defined by the appended claims. In someembodiments, well-known processes, structures, and technologies will notbe specifically described in order to avoid ambiguous interpretation ofthe present invention. Like reference numerals refer to like elementsthroughout the specification.

Spatially relative terms, such as “below”, “beneath”, “lower”, “above”,“upper”, and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation, in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” or “beneath” can encompassboth an orientation of above and below. The device may be otherwiseoriented and the spatially relative descriptors used herein interpretedaccordingly.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated components, steps, operations, and/or elements, butdo not preclude the presence or addition of one or more othercomponents, steps, operations, elements, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

First, a visible light communication apparatus according to the presentinvention will be briefly described before proceeding to a detaileddescription of the present invention. An exemplary visible lightcommunication apparatus according to the present invention is an imagedisplay apparatus (e.g., a liquid crystal display (LCD)) which includesa backlight that transmits data in addition to carrying out the typicalfunction of providing light to a display unit (e.g., a liquid crystalpanel). For the data transmission function of the backlight, a broadcastsignal into which an image signal and a data signal are multiplexed maybe output.

Hereinafter, a visible light communication apparatus according to anexemplary embodiment of the present invention will be described withreference to FIGS. 1 through 3.

FIG. 1 is a diagram illustrating the configuration of a visible lightcommunication apparatus 100 according to an exemplary embodiment of thepresent invention. FIG. 2 is a diagram illustrating examples of awaveform of a converted data signal according to an exemplary embodimentof the present invention. FIG. 3 is a diagram illustrating the conceptof image conversion performed by the visible light communicationapparatus 100 of FIG. 1.

Referring to FIG. 1, the visible light communication apparatus 100includes a broadcast signal reception unit 110, an image signalconversion unit 120, a display unit 130, a sensor unit 140, and a lightsource unit 150.

The broadcast signal reception unit 110 receives a broadcast signalthrough a cable, an antenna, power line communication (PLC), a localarea network (LAN), or the like, and checks whether the receivedbroadcast signal includes a data signal.

When the received broadcast signal does not include a data signal, thebroadcast signal reception unit 110 separates an image signal from thereceived broadcast signal and outputs the image signal to the displayunit 130. In this case, the visible light communication apparatus 100functions only as an image display apparatus.

When the received broadcast signal includes a data signal, the broadcastsignal reception unit 110 separates the image signal and the data signalfrom the received broadcast signal. It then outputs the image signal tothe display unit 130 and outputs the data signal to the light sourceunit 150.

The display unit 130 displays an image according to the input imagesignal and may be, for example, a liquid crystal panel. The display unit130 may display the image by projecting light emitted from the lightsource unit 150, which will be described later.

The sensor unit 140 is a touch-sensitive unit that senses whether aterminal desiring to receive the data signal has touched or approachedthe display unit 130. Here, the term ‘touch’ denotes that the terminalis in direct contact with the display unit 130, and the term ‘approach’denotes that the terminal is not in direct contact with the display unit130 but is close enough to cast a shadow on the display unit 130, forexample, located within approximately 10 cm from the display unit 130.To sense the touch or approach of the terminal, the sensor unit 140 maybe implemented as a touch panel or an illuminance sensor.

To sense the touch or approach of the terminal, the sensor unit 140 atwo-dimensional (2D) shape which corresponds to a touch surface or anapproach surface of the terminal which touches or approaches the displayunit 130. That is, the terminal will either contact an area of thedisplay unit 130, or cast a shadow upon it. Either way, the terminalwill have some effect upon a 2D area of the display unit 130. The sensorunit 140 may detect this region as follows.

For example, when the terminal touches the display unit 130, the sensorunit 140 may transmit a sensing signal to the display unit 130 frombehind the display unit 130, detect a 2D shape of the touched terminalbased on the terminal's reflection of the sensing signal, and determinethe region of the display unit 130 which corresponds to the detected 2Dshape. Alternatively, the sensor unit 140 may determine the 2D shape ofthe terminal by obtaining and combining information about all locationson the display unit 130 touched by the terminal, and may determine theregion of the display unit 130 which corresponds to the detected 2Dshape.

When the terminal does not touch but rather approaches the display unit130, the sensor unit 140 may sense the region of the display unit 130whose illuminance has changed due to the shadow of the terminal whichapproaches the display unit 130. That is, it may determine the 2D shapeof the shadow of the approaching terminal. It may also detect a regionof the display unit 130 which corresponds to the detected 2D shape.

Once it detects a region corresponding to the shape of the terminalwhich touches or approaches the display unit 130, the sensor unit 140outputs an image conversion signal to the image signal conversion unit120.

In response to the input image conversion signal, the image signalconversion unit 120 converts the image signal and outputs the convertedimage signal to the display unit 130. Here, the image signal conversionunit 120 converts the image signal such that the image displayed in theregion detected by the sensor unit 140 is converted into a bright image,that is, an image having a gray level higher than some predeterminedreference gray level. The display unit 130 displays an image accordingto the converted image signal. Thus, in the region corresponding to thedetected shape of the terminal, the display unit 130 displays its imageat a gray level higher than the reference gray level. If the imagealready has a gray level at or above the reference gray level, then theimage is left unmodified, i.e. if the image is already sufficientlybright, it is not further brightened. The need for such image conversionarises because when an image displayed on the display unit 130 is a darkimage having a low gray level (e.g., a full-black image), even if theterminal touches or approaches the display unit 130 to receive data, itis difficult for the terminal to sense an optical signal due to a lackof light, thus causing visible light communication to stop or to becompromised.

However, if image conversion is performed as in the current exemplaryembodiment, since a region of the display unit 130 which is touched orapproached by the terminal is a relatively bright region having a highgray level, there is sufficient light to carry out effective visiblelight communication. Accordingly, the terminal can easily sense anoptical signal, and thus visible light communication can be performedstably without interruption and at high speed. Additionally, the brightregion does not extend beyond the shape of the terminal. Therefore, theregion does not irritate a person who is watching an image displayed onthe display unit 130.

Here, an image having a gray level higher than the reference gray levelmay be defined as an image in which a gray value of a blue color (among,for example, red, green and blue (RGB) colors) is higher than apredetermined reference gray value, where the gray value can be anyvalue from 0 to 255 (the closer to 255, the higher the gray value). Thisis because a blue color wavelength has a high optical power value. Thatis, it is easier for the terminal to receive an optical signal from animage whose blue color has a high gray value.

An image having a gray level higher than the reference gray level may bea full-white image having an RGB gray value of (255, 255, 255) or afull-blue image having an RGB gray value of (0, 0, 255).

The light source unit 150 includes a light source 153, such as an LED,to provide light to the display unit 130. In addition, to transmit data,the light source unit 150 drives the light source 153 by turning on oroff the light source 153 based on the input data signal. That is, anoptical signal transmitted from the light source unit 150 to the displayunit 130 is generated based on the data signal.

The optical signal generated based on the data signal is transmitted toone or more terminals (not shown) which desire to receive data throughthe display unit 130. Although not shown in the drawings, a terminaldesiring to receive the data signal can include an optical sensor whichreceives an optical signal, and a demodulator which obtains the datasignal by demodulating the received optical signal.

As described above, the terminal touches or approaches the display unit130 to receive an optical signal generated based on a data signal.Accordingly, the communication range between the visible lightcommunication apparatus 100 and the terminal is reduced, therebyimproving communication quality.

The light source unit 150 includes a data converter 151, a light sourcedriver 152, and the light source 153.

The data converter 151 receives a data signal, converts the data signalbased on a data transmission protocol (e.g., the Ethernet protocol) thatcan be used in wireless optical communication, and outputs the converteddata signal to the light source driver 152. Here, the data signalconverted based on the data transmission protocol may be, for example, aseries of ON/OFF pulses.

The light source driver 152 drives the light source 153 according to theconverted data signal received from the data converter 151. The drivingof the light source 153 is accomplished by turning on or off the lightsource 153 using a frequency at which the flickering of the light source153 is unperceivable to the human eye. For example, when the lightsource driver 152 receives an ON/OFF pulse, the light source 153 may beturned on for a period of time corresponding to a pulse width of the ONsignal, and may be turned off for a period of time corresponding to apulse width of the OFF signal.

Here, the luminance of the light source 153 may be maintained or changedby adjusting the data transmission protocol. That is, the data converter151 may convert a data signal by adjusting the data transmissionprotocol in view of required luminance. For example, the pulse width ofthe data signal can be altered according to required luminance.Alternatively, the data signal can be divided into a luminance controlsection in addition to a data transmission section. Examples of awaveform of the converted data signal will now be described withreference to FIG. 2.

Referring to (a) and (b) of FIG. 2, the luminance of the light source153 can be reduced even though the same data pulses are transmitted.That is, the duration of the ON pulses can be increased or decreased,depending on whether the luminance of the light source 153 is to beraised or lowered. If the total ON time and the total OFF time of theconverted data signal are maintained, the luminance of the light source153 can be maintained unchanged. Here, the period of each bit ofinformation does not change. Thus, if the duration of the ON signal isreduced by a certain amount, the duration of the OFF signal is raised bythat same amount.

Alternatively, referring to (c) of FIG. 2, a converted data signal mayinclude a data transmission section, which is based on a data signalthat is to be actually transmitted, and a luminance control sectionwhich is to be used as a luminance control region, i.e., a dummy regionthat is not used for transmission of the data signal. The inventioncontemplates use of any bit sequences of any duration in the luminancecontrol region.

The invention is not limited to the above methods, and may employ anysuitable data transmission protocol used to convert data.

FIG. 3 is a diagram illustrating the concept of image conversionperformed by the visible light communication apparatus 100 of FIG. 1.Referring to FIG. 3, an image is displayed on the display unit 130 ofthe visible light communication apparatus 100, and the light source unit150 provides light to the display unit 130.

A terminal MT having an optical sensor touches or approaches the displayunit 130, in order to receive an optical signal corresponding to a datasignal. The sensor unit 140 detects region A1, corresponding to eitherthe terminal MT itself, or its shadow. The image area A1 is convertedinto a bright image, regardless of the remaining image A2. Accordingly,the optical signal reception quality of the terminal MT is improved.

FIG. 4 is a flowchart illustrating a visible light communication methodaccording to an exemplary embodiment of the present invention. Referringto FIG. 4, the broadcast signal reception unit 110 separates an imagesignal and a data signal from a broadcast signal, and outputs the imagesignal to the display unit 130 and the data signal to the light sourceunit 150 (operation S410). The display unit 130 displays an imageaccording to the input image signal, with the light source unit 150providing illumination as if it were a conventional backlight (operationS420). To fulfill this traditional backlight function, the light source153 can employ any suitable illumination source, such as LEDs or thelike.

Next, a terminal touches or approaches the display unit 130 (operationS430). The sensor unit 140 senses the touch or approach of the terminalon or to the display unit 130 by detecting a region corresponding to theshape of the terminal, and outputs an image conversion signal to theimage signal conversion unit 120 (operation S440).

In response to receiving the image conversion signal, the image signalconversion unit 120 converts the image signal such that the image of theregion detected by the sensor unit 140 is made brighter. That is, in theregion detected by sensor unit 140, the image is made brighter byraising its gray level above some predetermined reference gray level(operation S450).

In addition to acting as a conventional backlight, the light source unit150 also generates an optical signal by driving the light source 153based on the data signal, so as to output an additional optical signalto the display unit 130 (operation S460). A method used by the lightsource unit 150 to output the optical signal is as described above withreference to FIG. 1. That is, the light source unit 150 converts thedata signal to a series of light pulses according to a suitable datatransmission protocol, and emits the light pulses from light source 153.The light source unit 150 controls the luminance of the light source 153by adjusting the data transmission protocol. For example, the durationof each ON pulse can be increased or decreased as desired (up to themaximum duration of each data bit), to control the luminance of thislight source block relative to the other light source blocks. In thecontext of this invention, the term “average” may include not only anarithmetic average of luminance values, but also any luminance value inany way representative of any of the luminances of the remaining lightsource blocks. Furthermore, adjustments to the data transmissionprotocol may include the altering of any parameter of the protocol, suchas the period of each ON pulse, the period or frequency of the databits, or the like. Similarly, the luminance control section can employany duration and sequence of bits suitable for identifying a particulardesired luminance.

The operations included in the visible light communication methodaccording to the current exemplary embodiment need not necessarily beexecuted in the above order, and the order of the operations may vary.

Hereinafter, a visible light communication apparatus according toanother exemplary embodiment of the present invention will be describedwith reference to FIGS. 5 and 6. The visible light communicationapparatus according to the current exemplary embodiment transmits datathrough a partial region of a display unit, that is, through a displayblock of the display unit. In particular, same or different data may betransmitted through one or more display blocks. For simplicity, adescription of elements substantially identical to those of the previousembodiment described above with reference to FIGS. 1 through 3 will beomitted or simplified.

FIG. 5 is a diagram illustrating the configuration of a visible lightcommunication apparatus 500 according to another exemplary embodiment ofthe present invention. Referring to FIG. 5, the visible lightcommunication apparatus 500 includes a broadcast signal reception unit510, an image signal conversion unit 520, a display unit 530, a sensorunit 540, and a light source unit 550.

The broadcast signal reception unit 510 receives a broadcast signal andseparates an image signal and a data signal from the received broadcastsignal. Then, the broadcast signal reception unit 510 outputs the imagesignal to the display unit 530 and the data signal to the light sourceunit 550.

The display unit 530 includes a plurality of display blocks whichdisplay an image according to the input image signal. The display unit530 according to the current exemplary embodiment includes 3×3 displayblocks, although any number and layout of such blocks is contemplated.

The sensor unit 540 senses whether a terminal desiring to receive thedata signal has touched or approached the display unit 530. The sensorunit 540 also determines which display block corresponds to the locationtouched or approached by the terminal, and

outputs information about the detected display block to a light sourcedriver 552 such that a light source block corresponding to the detecteddisplay block can be driven.

In addition to the function of detecting a terminal and determining thedisplay block it touches/approaches, the sensor unit 540 may perform thefunction of the sensor unit 140 shown in FIG. 1. That is, the sensorunit 540 may detect a region corresponding to the shape of the terminalwhich touches or approaches the display unit 530, and may output animage conversion signal to the image signal conversion unit 520 so as tobrighten the image displayed in the detected region. In response to theinput image conversion signal, the image signal conversion unit 520converts the image signal such that the image of the region detected bythe sensor unit 540 is converted into a bright image, that is, an imagehaving a gray level higher than a predetermined reference gray level,and outputs the converted image signal to the display unit 530. If theimage already has a gray level at or above the reference gray level,then the image is left unmodified, i.e. if the image is alreadysufficiently bright, it is not further brightened. Since this imageconversion process has been described above with reference to FIG. 1, adetailed description thereof will be omitted.

The light source unit 550 includes a plurality of light source blockscorresponding respectively to the display blocks of the display unit530. Thus, the light source unit 550 of the current exemplary embodimentincludes a 3×3 grid of light source blocks. Each of the light sourceblocks provides light to a corresponding one of the display blocks.Here, at least one of the light source blocks transmits data by beingturned on or off based on the input data signal. That is, That is, aterminal may touch or approach any one of the display blocks of thedisplay unit 530 and receive an optical signal, which is based on a datasignal, from the corresponding light source block.

Specifically, the light source unit 550 includes a data converter 551,the light source driver 552, and a light source 553 having a pluralityof light source blocks.

The data converter 551 receives a data signal, converts the data signalbased on a data transmission protocol such as a wireless opticalcommunication protocol, and outputs the converted data signal to thelight source driver 552. The light source driver 552 then drives theappropriate block of light source 553 according to this data signal.

Here, the luminance of a light source block may be varied by adjustingparameters of the data transmission protocol. That is, the luminance ofa light source block may be adjusted at least partially according to theaverage luminance of the other light source blocks.

FIG. 6 is a diagram illustrating the concept of data transmissionperformed by the visible light communication apparatus 500 of FIG. 5.Referring to FIG. 6, an image is displayed on the display unit 530 ofthe visible light communication apparatus 500. The light source unit 550provides light to the display unit 530 via a plurality of light sourceblocks, each of which illuminates a respective display block of thedisplay unit 530.

A terminal MT having an optical sensor touches or approaches any one ofthe display blocks of the display unit 530 to receive a data signal. Forexample, terminals MT1 and MT2 may respectively touch or approachdifferent display blocks B1 and B2, as shown in the drawing.

When the terminal MT1 touches or approaches the display block B1, thelight source block located behind block B1 is driven according to a datasignal, so as to transmit data to terminal MT1. Thus, the terminal MT1can receive an optical signal, which is generated based on the datasignal, from the display block B1.

Similarly, when the terminal MT2 touches or approaches the display blockB2, the light source block located behind block B2 is driven accordingto a data signal, so as to transmit data to terminal MT2. Thus, theterminal MT2 can receive an optical signal, which is generated based onthe data signal, from the display block B2. Here, the data signal whichdrives the light source block behind display block B2 may be the same ordifferent from the data signal which drives the light source blockbehind display block B1.

The regions corresponding to the shapes of each of the terminals MT1 andMT2 display a brighter image having a higher gray level, as describedabove with reference to FIG. 3.

FIG. 7 is a flowchart illustrating a visible light communication methodaccording to another exemplary embodiment of the present invention.Referring to FIG. 7, the broadcast signal reception unit 510 separatesan image signal and a data signal from a broadcast signal, and outputsthe image signal to the display unit 530 and the data signal to thelight source unit 550 (operation S710). Here, the display unit 530includes a plurality of display blocks, and the light source unit 550includes a plurality of light source blocks each positioned toilluminate one of the display blocks.

The display unit 530 displays an image according to the input imagesignal, with each of the light source blocks of the light source unit550 providing light to its corresponding display block in the samemanner as a conventional backlight (operation S720).

A terminal can be brought into contact, or near contact, with any one ofthe display blocks of the display unit 530 in order to receive data froman optical signal that is generated based on the data signal (operationS730). The sensor unit 540 detects the area of the terminal or theterminal's shadow, identifies the display block that this terminaltouches/approaches, and outputs a signal for driving the correspondinglight source block (operation S740).

The light source unit 550 receives this signal, generates an opticalsignal based on the input data signal, and outputs this optical signalto the detected display block (operation S750). A method used by thelight source unit 550 to output the optical signal is as described abovewith reference to FIG. 1. That is, the light source block correspondingto the detected display block is turned on or off so as to generatelight pulses that correspond to the binary data signal. The overallluminance of the light source block is controlled by adjusting the datatransmission protocol. Here, the luminance of the light source blockwhich is driven based on the data signal may be controlled in view ofthe average luminance of the other light source blocks. For example, theduration of each ON pulse can be increased or decreased as desired (upto the maximum duration of each data bit), to control the luminance ofthis light source block relative to the other light source blocks. Inthe context of this invention, the term “average” may include not onlyan arithmetic average of luminance values, but also any luminance valuein any way representative of any of the luminances of the remaininglight source blocks. Furthermore, adjustments to the data transmissionprotocol may include the altering of any parameter of the protocol, suchas the period of each ON pulse, the period or frequency of the databits, or the like. Similarly, the luminance control section can employany duration and sequence of bits suitable for identifying a particulardesired luminance.

Although not shown in the drawing, operations S440 and S450 describedabove with reference to FIG. 4 may additionally be performed afteroperation S730. That is, an operation in which the sensor unit 540detects a region corresponding to the shape of the terminal whichtouches or approaches the display unit 530 and an operation in which theimage signal conversion unit 520 converts an image of the regiondetected by the sensor unit 540 into a bright image may additionally beperformed.

The operations included in the visible light communication methodaccording to the current exemplary embodiment may not necessarily beexecuted in the above order, and the order of the operations may vary.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetail may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims. Theexemplary embodiments should be considered in a descriptive sense onlyand not for purposes of limitation.

1. A visible light communication apparatus, comprising: a display unitthat displays an image according to an image signal; a light source unitthat operates as a backlight for the display unit, generates an opticalsignal by driving a light source based on a data signal, and outputs thegenerated optical signal to the display unit; a sensor unit that detectsa region corresponding to a shape of a terminal which touches orapproaches the display unit; and an image signal conversion unit thatconverts the image signal such that an image displayed in the regiondetected by the sensor unit is converted to a bright image having a graylevel higher than a predetermined reference gray level.
 2. The apparatusof claim 1, wherein the bright image is an image in which a gray levelof a blue color is higher than the predetermined reference gray level.3. The apparatus of claim 2, wherein the bright image is a full-whiteimage or a full-blue image.
 4. The apparatus of claim 1, wherein thelight source unit comprises: a data converter that converts the datasignal according to a predetermined data transmission protocol, so as togenerate a converted data signal; and a light source driver driving thelight source according to the converted data signal, wherein the dataconverter adjusts the data transmission protocol according to aluminance of the light source.
 5. The apparatus of claim 1, wherein theterminal comprises: an optical sensor receiving the optical signal; anda demodulator determining the data signal by demodulating the receivedoptical signal.
 6. A visible light communication apparatus, comprising:a display unit having a plurality of display blocks on which an image isto be displayed; a light source unit having a plurality of light sourceblocks which correspond respectively to the display blocks, wherein eachof the light source blocks is configured to output an optical signal toa corresponding one of the display blocks; and a sensor unit thatidentifies a display block corresponding to a position of a terminalwhich touches or approaches the display unit, wherein the light sourceunit is configured to generate an optical signal by driving the lightsource block corresponding to the identified display block, wherein thedriving is based on a data signal of a broadcast signal, and wherein thedriving outputs the generated optical signal to the identified displayblock.
 7. The apparatus of claim 6, wherein the sensor unit isconfigured to detect a region of the display unit corresponding to ashape of the terminal, and wherein the apparatus further comprises animage signal conversion unit for converting an image signal such that animage displayed in the region detected by the sensor unit is convertedto a bright image having a gray level higher than a predeterminedreference gray level.
 8. The apparatus of claim 6, wherein the lightsource unit comprises: a data converter for converting the data signalaccording to a predetermined data transmission protocol, so as togenerate a converted data signal; and a light source driver driving thelight source block according to the converted data signal, wherein thedata converter is configured to adjust the data transmission protocolaccording to a luminance of the light source block.
 9. The apparatus ofclaim 7, wherein the bright image is an image in which a gray level of ablue color is higher than a predetermined reference gray level.
 10. Theapparatus of claim 9, wherein the bright image is a full-white image ora full-blue image.
 11. The apparatus of claim 6, wherein the terminalcomprises: an optical sensor receiving the optical signal; and ademodulator determining the data signal by demodulating the receivedoptical signal.
 12. A visible light communication method, comprising:displaying an image on a display unit according to an image signal;detecting a terminal touching or approaching the display unit; detectinga region corresponding to a shape of the terminal that touches orapproaches the display unit; converting the image signal such that animage displayed in the detected region is converted to a bright imagehaving a gray level higher than a predetermined reference gray level;generating an optical signal by driving a light source based on a datasignal; and outputting the generated optical signal to the display unit.13. The method of claim 12, wherein the bright image is an image inwhich a gray level of a blue color is higher than a predeterminedreference gray level.
 14. The method of claim 12, wherein the generatingof the optical signal and the outputting of the generated optical signalto the display unit comprises: converting the data signal according to apredetermined data transmission protocol; and driving the light sourceaccording to the converted data signal, wherein the data transmissionprotocol is adjusted according to a luminance of the light source.
 15. Avisible light communication method, comprising: displaying an image on adisplay unit according to an image signal, the display unit having aplurality of display blocks; detecting a terminal touching orapproaching any one of the display blocks; identifying a display blockcorresponding to a position of the touching or approaching terminal;generating an optical signal by driving a light source block thatcorresponds to the identified display block, wherein the driving isbased on a data signal; and outputting the generated optical signal tothe identified display block.
 16. The method of claim 15 furthercomprising, after the detecting a terminal: detecting a regioncorresponding to a shape of the touching or approaching terminal; andconverting the image signal such that an image displayed in the detectedregion is converted to a bright image having a gray level higher than apredetermined reference gray level.
 17. The method of claim 16, whereinthe bright image is an image in which a gray level of a blue color ishigher than a predetermined reference gray level.
 18. The method ofclaim 15, wherein the generating of the optical signal and theoutputting of the generated optical signal to the detected display blockcomprise: converting the data signal according to a predetermined datatransmission protocol; and driving the light source block according tothe converted data signal, wherein the data transmission protocol isadjusted according to a luminance of the light source block.